Large underground oil shale deposits are found both in the US and around the world. In contrast to petroleum deposits, these oil shale deposits are characterized by their solid state; in which the organic material is a polymer-like structure often referred to as “kerogen” intimately mixed with inorganic mineral components. Heating oil shale deposits to a temperature of about 300 C. has been shown to result in the pyrolysis of the solid kerogen to form petroleum-like “shale oil” and natural-gas like gaseous products. The economic extraction of products derived from oil shale is hindered, in part, by the difficulty in efficiently heating underground oil shale deposits.
Thus there is a need in the art for a method and apparatus that permits the efficient in situ heating of large volumes of oil-shale deposits.